In the watering of lawns and gardens, it is convenient to have a means for automatically turning the water on and off, particularly where there are several watering sections that must be sequentially turned on and off. Commonly used systems for sequentially turning on and off a series of watering sections comprise a solenoid controlled valve for each watering section, with the respective solenoid controlled valves connected to a common fluid source. An electric control system controls the solenoid valves by electrically signalling the valves to turn on or turn off. Thus, it is possible to program the beginning time and watering time for each watering section. The problem with these systems is that the length of watering time for lawns and gardens is ideally determined by the amount of water passing through the valve to the lawn, rather than a set watering time as provided by these systems. In addition, the amount of water delivered to the lawn is dependent upon the water pressure. When the fluid pressure is lower than normal and the rate of fluid flow is less, the lawn or garden may be underwatered. In addition, the electric solenoid systems are expensive and are adapted primarily for in-ground water irrigation systems, and are not easily used by those watering with a hose connected to a hose bib.
Other devices used for the automatic watering, are metered water timers. Examples of metered water timers are described in U.S. Pat. Nos. 2,929,534, 3,097,762, 3,473,695, 3,187,943, 3,169,666, and 4,708,264. These devices generally function by metering the water as it passes through the valve. The valves are operated by manually setting and opening the valve. After the amount of water passing through the valve reaches a preset amount, the valve automatically shuts off the fluid flow. Thus, these valves are not fully automatic as they require manual resetting and restarting after a watering sequence in finished.
Metered valves have the advantage of having the watering time based upon fluid flow instead of a fixed time. However, these prior-art metered timers are not easily adapted for use with multiple watering sections. One may have several timers connected to a water source for different watering sections, but to water the different sections sequentially, one must manually start each timer after the preceding timer has finished its cycle. Thus, a fully automatic watering sequence is not possible with these valves. While it is possible to combine these valves with a mechanical or electronic timer to automatically open these valves at a preset time, fully automatic operation is still difficult. Each timer/valve combination operates independently, thus, each timer and valve must be carefully programmed separately to prevent overlapping watering times. In addition, the adding of the timer to the valve lowers the mechanical reliability and increases the cost of the system.